The invention concerns a winder for the winding of a running web of paper, foil or the like. A backing roll, a winding drum on which the web is wound into a roll, and a first pair of swivel levers (primary levers) are utilized in the winder. The primary levers each feature on an end a fork for receiving a journal of the winding drum, and are mounted with the other end in the area of the backing roll axis in such a way that the winding roll, in swiveling from a first position above the backing roll in the running direction of the web about the backing roll, approaches the latter and passes a primary section. The winding roll then reaches a second position in which the winding drum, with the as yet incomplete paper roll, is taken over by a second pair of swivel levers (secondary levers), with an essentially horizontal guideway extending from the second position via a secondary setting to a third position. A contact pressure device forces the winding drum with the paper roll being created thereon onto the backing roll.
Such winders, also called "Pope rollers," form generally the final section of a paper machine, serving to fashion the paper web accruing there into a roll form. But they are also used for rewinding an already completed roll so as to create a new roll.
In each case, the roll is to have very specific properties, particularly as concerns the winding hardness. Starting from a certain initial value, the winding hardness is to diminish to a limit value. This reduction is supposed to be maximally uniform from the first lap to the last. The reduction is to exhibit a specific gradient, i.e., it should not be too heavy nor should it be too light. The progression of the winding hardness should at no rate display jumps, such as a sudden drop.
All of this has so far been sought but not achieved. Instead, winders of known design produce rolls where the core is extremely hard. As a result, this core becomes unusable because the web is overextended in this area and breaks, so that this part must be discarded as scrap.
Prior means for influencing the winding hardness are two measures which are used, for instance, on slitters. One measure provides for subjecting the web during winding to a more or less heavy tension. The other measure consists in forcing the roll more or less heavily down on the backing roll, for instance by applying pressure on the axles of the winding drum or by applying contact pressure with a rider roll which is arranged parallel to the roll created and forced on it, so that a line pressure is created between the paper roll and the backing roll.
Frequently, a line pressure is generated between the roll being created and the backing roll, in the said primary section, by the weight of the paper roll. The paper roll is extremely heavy, reaching a dead weight of several tons, so that a correspondingly high line pressure is created. This line pressure is responsible for the extremely high winding hardness of the core of the roll.
In order to somewhat reduce the line pressure, and thus also the winding hardness in the core area, relief devices for the winding drum/paper roll have already been used which are supposed to act in the sense of uplifting the winding drum/paper roll and thus of a reduction of the line pressure. Theoretically, this is the case. Due to the inevitable vibrations of the entire machine during operation, however, a "dancing" occurs so that the relief can be performed only with care--and thus with little effectiveness--in order to prevent the winding drum/paper roll from jumping out of the forks of the first two swivel levers.
Thus, the problem of the excessively hard core has so far remained unmanageable. The problem could not be solved either by accelerating the winding drum/paper roll prior to unwinding a new roll, to winding speed, in the upper apex area of the backing roll until the peripheral speed of the winding drum/paper roll and backing roll were synchronized. Neither has it so far been possible to solve the other problem, namely the. aforementioned steep drop of the winding hardness in the limit range. Especially unfavorable in the course of the entire winding is the time span of transferring the created roll from the primary section to the secondary section. During this time span, the winding hardness is practically outside any control.
The problem underlying the invention is to give a winder a design such that the winding hardness will have the desired progression from start to completion of the roll, i.e., that the extreme hardness in the core area will be avoided, and that the winding hardness is under control at any moment of the winding process. Additionally, of course, the mechanical expense is to be held as low as possible.